In a long term evolution (abbreviated as LTE) system, a user equipment (abbreviated as UE) is required to transmit a sounding signal to an evolved base station (Evolved NodeB, abbreviated as eNodeB), so that the eNodeB can perform an uplink channel estimation according to the sounding signal.
In the prior art, procedures of triggering an UE to transmit a sounding signal by an eNodeB are: the eNodeB transmits a physical downlink control channel (abbreviated as PDCCH) to the UE, where the PDCCH bears downlink control information (abbreviated as DCI). Once the UE has detected the DCI borne by the PDCCH, the UE can transmit the sounding signal to the eNodeB.
Nevertheless, in the prior art, an eNodeB can only trigger one UE to transmit a sounding signal on a PDCCH, the efficiency is comparatively low.